Being the largest organ, the human skin acts as a barrier that protects the body against many harmful factors such as temperature, moisture, ultraviolet (UV) light, etc. from external environment. The skin may be aged or damaged due to various factors. In particular, it is known that heat accelerates skin aging by increasing the temperature of the skin, triggering various inflammatory responses and degrading collagen in the dermis by inducing increase of collagenases.
In order to avoid or prevent skin damage caused by heat, a standard for evaluating the ability of preventing thermal skin aging is required. Although sun protection factor (SPF) is available as an index for the ability of protecting from UV, a material which provides protection from UV may not provide protection from heat, and vice versa. Therefore, a standard for evaluating the ability of preventing thermal skin damage is needed.